System and method for component interconnection in HPLC

ABSTRACT

A system for component interconnection for use in liquid chromatography includes a first switching valve and a second switching valve. A first connecting line fluidly connects the first switching valve to the second switching valve. A second connecting line fluidly connects the first switching valve to the second switching valve. A metering device is located in the first connecting line.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the priority benefit under 35 U.S.C. § 119 toGerman Patent Application No. DE 10 2016 121 519.8, filed on Nov. 10,2016, the disclosure of which is incorporated herein by reference.

FIELD OF THE INVENTION

The invention relates to component interconnection, particularly in HighPerformance Liquid Chromatography (HPLC). More precisely, the inventionrelates to a valve switching mechanism for HPLC systems.

BACKGROUND

In High Performance Liquid Chromatography (HPLC), a sample to beanalysed is passed through a chromatography column to be separated intoits constituent parts. The sample separation is generally performed inthe chromatography, or analytical column (also called separation column)at high pressure. Such pressure can be on the order of a few hundredbar, or about a 1000 bar, or even more, such as 1500 bar. The sample canbe pushed through the separation column by a pump. During the samplemovement through the column, its individual constituents interactdifferently with the material packed in the column (usually granularmaterial). In this way, different sample constituents move through theseparation column at different speeds and can be separately measured.Before reaching the separation column, the sample must generally beintroduced into a liquid chromatography system from a sample reservoir.

Before a sample is loaded into the separation column, it can passthrough several other components of a liquid chromatography system.Those can comprise a sampler, a sample loop, a trap column and varioustubing or capillaries, although not all components need to be present inevery liquid chromatography system. To ensure that the system remainspressurized and to guarantee a leak proof system minimizing deadvolumes, sophisticated connection mechanisms are needed in such systems.

U.S. Pat. No. 8,677,808 B2 discloses, in one embodiment, a sampleinjection system including a vacuum source, a conduit in communicationwith the vacuum source, a fluid sensor configured to detect the presenceof the fluid in the conduit, a sample loop in communication with theconduit; and a sipper in communication with the sample loop.

U.S. Pat. No. 8,806,922 B2 discloses a sample injector for liquidchromatography including an injection valve having a waste port, twosample loop ports, and two high-pressure ports. One high-pressure portcan be connected to a pump and the other high-pressure port can beconnected to a chromatography column. A sample loop is connected to oneof the sample loop ports on one end and to a pump volume of a sampleconveying device on the other end. A section of the sample loop can beseparated to facilitate receiving a sample fluid in the sample loop. Acontrol unit controls the injection valve and the sample conveyingdevice. The sample injector allows a sample to be loaded into the sampleloop and then pressurized to an operating pressure prior to injectingthe sample into the chromatography column. The sample loop may also beisolated from the operating pressure for facilitating depressurizationof the loop.

Liquid chromatography systems often use switching valves to fluidlyconnect various system components with each other. In other words,switching valves are responsible for connection and separation of fluidpaths or ports where HPLC components are connected. Such valves can beadvantageous, as they can be manufactured to withstand sufficientpressures and to be leak-proof. Generally, valves in liquidchromatography are also adapted to minimize dead volumes, or spaceswhere liquid can gather and remain. Such valves can for example comprise“ports” and “grooves”. A component of the system can be fluidlyconnected to a particular port. Grooves can be used to connect two portswith each other. A valve in a liquid chromatography system can alsocomprise several switching positions, that is, several configurationswhich allow for interconnecting of different system components. Forexample, this can be achieved by having system elements fixedlyconnected to individual ports and using grooves to fluidly connect saidports to each other in different configurations. Some liquidchromatography systems may comprise a plurality of valves for componentinterconnection, such as two valves. This allows for a larger margin ofmanoeuvre and flexibility in interconnecting system components.

In some prior art, only one switching valve is used to interconnect thecomponents in the various process steps.

SUMMARY

Different configurations or switching positions of switching valvesallow for different steps of sample loading and system operation in aliquid chromatography system. For example, in a “load” switchingposition it should be possible to draw up a sample in the sample loop.This can be done via a pump or a metering device. If a trap column forsample filtering and concentration is present, a certain valveconfiguration should allow for sample trapping within it (i.e.,transporting sample into the trap column). Another valve position couldallow pre-compressing of the trap column (and subsequent decompressing)before bringing the sample into the analytical flow via an “inject”valve position. Some other switching positions could allow for pumppurging and/or system washing.

Some problems arising with the valves described in the prior art arelisted below. Not every problem occurs for every execution.

During sample analysis, the fluidic components including the trap columncannot be cleaned and the trap column cannot be loaded. That is, sampleanalysis on the one hand and cleaning and/or loading cannot be performedsimultaneously.

The need to achieve two dead ends for pressure build-up during thepre-compressing of the sample, often leads to a valve design comprisingprolonged grooves with an intermediate valve position. This can lead tosample dispersion, gradient distortion and carry-over.

The washing of the fluidics is often done with an additional washing orcleaning pump, requiring another separate component of the system and avalve port to connect it to.

The trapping of the sample is often done with an additional loadingpump, requiring another separate component of the system and a valveport to connect it to.

Changing a solvent or a cleaning fluid can require hardware changes insome prior art, or manually replacing the solvent or cleaning fluidreservoir. That is, in some prior art it was not possible to freelychoose a solvent or a cleaning fluid during the trapping or the washingphases.

In light of the above, it is an object of the present invention toprovide a valve switching system and method for High Performance LiquidChromatography allowing for multiple advantageous improvements. Inparticular, said system may allow for washing and reloading of thefluidic components and the trap column during sample analysis, avoidingnon-thoroughly cleaned grooves and areas in which dead volume canassemble, avoiding the use of a further pump aside from the analyticalpump and the metering device, and choosing freely a solvent and/or awashing solution. That is, it is an object of the present invention toovercome or at least alleviate the shortcomings and disadvantages of theprior art. In particular, it is an object of the present invention toprovide a system for component interconnection for use in liquidchromatography and a corresponding method having improvedcharacteristics as regards versatility, reduction of complexity, failsafety and simplicity of use and service.

Inter alia, the invention relates to two interconnected switching valveswith an integrated metering device for liquid chromatography,particularly for high pressure liquid chromatography (HPLC). In otherwords, the invention relates to two switching valves connected by atleast two connecting lines, with a metering device integrated on atleast one connecting line. The connecting lines can also be separable,for example through a needle connecting with a needle seat.

The present invention is specified in the claims as well as in the belowdescription. Preferred embodiments are particularly specified in thedependent claims and the description of various embodiments.

According to a first aspect, the present invention relates to a systemfor component interconnection for use in Liquid Chromatography. Thesystem comprises a first switching valve; and a second switching valve;and a first connecting line fluidly connecting the first switching valveto the second switching valve and a second connecting line fluidlyconnecting the first switching valve to the second switching valve; anda metering device located in the first connecting line.

This system design with two switching valves, two connecting lines and ametering device disposed in one connecting line may allow the system toassume a configuration simultaneously allowing a sample to be analyzedand the trap column to be reloaded. Furthermore, it may also allowsimultaneous sample analysis and washing of components including, forexample, the trap column. Further still, by means of the discusseddesign, the overall number of pumps may be reduced. In particular, itmay be possible for such a system to only use the metering device andone additional pump. That is, such a system may use two pumps only. Thismay be different to some prior art systems making use of a greaternumber of pumps. Having a reduced number of pumps may render the systemof the present invention less complex than prior art systems. This mayincrease the efficiency of the system, make the system more fail safe(as there are fewer components that may malfunction) and simpler toservice (as there are fewer components subject to wear).

Each switching valve may comprise at least four ports and at least twoconnecting elements, preferably at least five ports and at least threeconnecting elements.

The system may further comprise an analytical pump adapted to generatean analytical flow in the system.

The system may further comprise a separation column.

The system may further comprise a trap column.

The system may further comprise a sample pick up means adapted toretrieve a sample and a seat adapted to receive the sample pick upmeans.

The system may be adapted to connect the metering device to a samplereservoir via the sample pick up means in a sample draw position.

That is, the metering device may be adapted to draw in sample in thisposition.

The second switching valve may be adapted to connect the metering devicewith a dead end via the first connecting line in a sample draw position.

The metering device may be adapted to generate negative pressure drawingin a sample in the sample draw position.

The second switching valve may be adapted to connect the metering deviceand the first switching valve to dead-ends via the first connecting lineand the second connecting line respectively in a pre-compressingposition.

The metering device may be adapted to generate positive pressurepre-compressing components connected via the first switching valveincluding the sample in the pre-compressing position.

That is, the metering device may be used to pre-compress the system.This may be different to some prior art systems, where another device(typically a pump) was used to pre-pressurize the system. Thus, lesscomponents may be employed by the present system, thereby reducing thecomplexity of the present system.

The metering device may be adapted to pre-compress the sample to apressure of a least 100 bar, such as at least 1000 bar, more preferablyabout 1500 bar.

The first switching valve may be adapted to simultaneously connect theanalytical pump with the trap column and the trap column with theseparation column in a sample inject position.

The second switching valve may be adapted to connect the metering deviceto at least one solvent reservoir, preferably to two distinct solventreservoirs via the first connecting line in a washing position. Thus,different solvents may be used in the present system without having tomanually connect another solvent reservoir to the system.

The metering device may be adapted to wash components connected via thefirst switching valve and the second switching valve in the washingposition during sample analysis.

That is, component washing may be performed simultaneously to the sampleanalysis, thereby reducing the time required for sample analysis andwashing, which may improve the efficiency of the system.

The system may be adapted to be reloaded with a new sample via themetering device in a reload position during sample analysis in the trapcolumn.

Again, the present system allows these steps to be performedsimultaneously, thereby saving time and enhancing the efficiency.

The system may further comprise a waste reservoir.

The system may further be adapted to fluidly connect the analytical pumpwith the waste reservoir via the second connecting line in a pump purgeposition.

The system may be adapted for high performance liquid chromatography.

The first switching valve may be adapted to assume at least two distinctswitching positions.

The second switching valve may be adapted to assume at least threedistinct switching positions.

One port of the first switching valve may be directly fluidly connectedto the seat and to the first connecting line; and two ports of the firstswitching valve may be directly fluidly connected to the trap column;and one port of the first switching valve may be directly fluidlyconnected to the separation column; and one port of the first switchingvalve may be directly fluidly connected to the analytical pump; and oneport of the first switching valve may be directly fluidly connected tothe second connecting line.

The term “direct fluid connection” or “directly fluidly connected” isused herein. When a port of a valve is said to be directly fluidlyconnected to another component, this should denote that fluid may flowfrom the port to the other component (and/or vice versa) without havingto pass another port.

One port of the second switching valve may be directly fluidly connectedto the waste reservoir; and one port of the second switching valve maybe directly fluidly connected to the first solvent reservoir; and oneport of the second switching valve may be directly fluidly connected tothe first connecting line; and one port of the second switching valvemay be directly fluidly connected to the second connecting line.

The system may further comprise a second solvent reservoir and one portof the second switching valve may be directly fluidly connected to thesecond solvent reservoir.

The first connecting line may comprise one end fluidly connected to thesecond switching valve; and tubing connecting the second switching valveto the metering device; and tubing connecting the metering device to thesample pick up means.

The first connecting line may be adapted to be separable via the samplepick up means and the seat.

Note, that connecting lines can also be separable. That is, a connectingline need not always connect the first valve to the second, but caninterrupt this connection for some other function. For example, incertain preferred embodiments, the first connecting line is separable.This can be realized via the sample pick up means and the seat that canbe located on the first connecting line. In the stand by position, thesample pick up means rests in the seat, ensuring that the firstconnecting lines is whole and is connecting the first and secondswitching valves. When, however, the sample pick up means moves to thesample reservoir in order to retrieve the sample, the first connectingline is separated between the sample pick up means and the seat. Whenthe sample pick up means returns to the seat with the sample, the firstconnecting line is whole again.

The first switching valve may have an identical design as the secondswitching valve. This may lead to a particularly simple and efficientproduction process.

At least one of the first and the second switching valve may comprise atleast one blind plug.

The present invention also relates to a use of the liquid chromatographysystem discussed above. Such a use may yield corresponding benefits asthe system discussed above.

The second switching valve may switch the first connecting line to thesolvent reservoir and the second connecting line to a dead end, and themetering device may generate negative pressure drawing in the solvent.

That is, the metering device may be used to draw in solvent.

The second switching valve may switch the first connecting line to adead end, and the metering device may generate negative pressure forsample retrieval.

That is, the metering device is used to draw in sample into the system.

The second switching valve may switch the first connecting line and thesecond connecting line to dead ends, and the metering device maygenerate positive pressure for pre-compressing the trap column with thesample.

Thus, the metering device may also be used to pre-pressurize the system,which may omit the necessity of another pump for this purpose, therebyreducing the complexity of the system vis-à-vis prior art systems.

The second switching valve may switch the first connecting line and thesecond connecting line to dead ends, and the metering device maygenerate negative pressure for decompressing the trap column.

That is, the metering device may also be used for this purpose and thus,the complexity of the system may be further reduced.

The first switching valve may connect the first connecting line and thesecond connecting line with two sides of the trap column, and the secondswitching valve may connect the first connecting line with a dead endand the second connecting line with the waste reservoir, and themetering device may wash the trap column and the connecting lines.

Thus, the metering device may also be used to wash the components,thereby further reducing the need for further components and alsoreducing the complexity of the system.

The first switching valve may connect the analytical pump with thesecond connecting line and the second switching valve may connect thesecond connecting line with the waste reservoir, and the analytical pumpmay provide a flow to clean itself.

The use is may be use in liquid chromatography.

The use may be in high performance liquid chromatography.

The present invention also relates to a method for sample loading. Themethod comprises the steps of

a. providing a liquid chromatography system comprising a first switchingvalve, a second switching valve, a first connecting line fluidlyconnecting the first switching valve to the second switching valve and asecond connecting line fluidly connecting the first switching valve tothe second switching valve, a metering device located in the firstconnecting line, a separation column, a trap column, and an analyticalpump; and

b. loading a sample into the trap column; and

c. fluidly connecting the trap column to the separation column and theanalytical pump to the trap column via the first switching valve andgenerating a flow from the analytical pump to the separation column.

That is, the system, which may comprise any of the features recitedabove, may be employed in a method for sample loading to also arrive atbenefits corresponding to the ones discussed above.

The method may further comprise

d. fluidly connecting the analytical pump to the separation column,wherein the trap column is not fluidly connected to the analytical pumpor the separation column, and maintaining the flow from the analyticalpump to the separation column.

That is, in this configuration, fluid may flow “directly” from theanalytical pump to the separation column without passing the trapcolumn.

The method may further comprise

e. washing the trap column and the connecting lines; and/or

f. loading another sample into the trap column.

The liquid chromatography system may further comprise a sample pick upmeans adapted to retrieve the sample and a seat adapted to receive thesample pick up means.

Step b. may comprise the sample pick up means being moved to a samplereservoir, the sample being sucked into the sample pick up means andinto a tubing section adjacent to the sample pick up means, the samplepick up means being moved to the seat, the first switching valve beingset to provide a fluid connection between the seat and the trap column,the sample being introduced into the trap column.

The sample may be sucked into the sample pick up means by means of themetering device generating negative pressure.

The sample may be introduced into the trap column by connecting thefirst connecting line to a dead end via the second switching valve andto the trap column via the first switching valve, and the meteringdevice pushing the sample from the first connecting line to the trapcolumn by generating positive pressure.

The liquid chromatography system may further comprise a waste reservoir.

Step e. may comprise fluidly connecting the first connecting line to adead end via the second switching valve and to the trap column via thefirst switching valve, and the second connecting line to the trap columnvia the first switching valve and to the waste reservoir via the secondswitching valve, and generating a flow from the metering device to thewaste reservoir.

Step d. may be performed concurrently with steps e. and/or f. Thus, theefficiency of the present method may be increased vis-à-vis such methodswhere such steps are performed one after the other.

The method may comprise pressurizing the trap column after loading thesample into it.

The trap column may be pressurized when the trap column is not fluidlyconnected to the analytical pump. That is, the trap column may bepressurized in a controller manner, thereby reducing pressure spikes (atthe trap column) and pressure spikes and drops in the separation column.This may reduce the wear of these components (to thereby increase theirservice life). Furthermore, the controlled compression may reduce samplebeing dispersed, finally resulting in more defined peaks in subsequentanalysis.

The trap column may be pressurized when the trap column is not fluidlyconnected to the separation column.

The metering device may pressurize the trap column. Thus, no furthercomponent may be needed for this purpose, reducing the complexity of thesystem.

The method may comprise depressurizing the trap column after supplyingthe sample from the trap column to the separation column.

The trap column may be depressurized when the trap column is not fluidlyconnected to the analytical pump.

The trap column may be depressurized when the trap column is not fluidlyconnected to the separation column.

The metering device may depressurize the trap column. All of themeasures recited in the three preceding paragraphs may lead to acontrolled decompression. This may be beneficial, as it may reduce thewear of the components vis-à-vis an uncontrolled and typically morerapid depressurization. Furthermore, it may also reduce the likelihoodof fluids exiting the system rapidly (and potentially causing harm tousers) and the likelihood of constituents outgassing.

The trap column may be pressurized to a pressure of at least 100 bar,preferably 1000 bar, more preferably at least 1500 bar.

The metering device may load the sample into the trap column.

The metering device may wash the trap column and the connecting lines bygenerating positive pressure. Again, by having such additionalfunctionalities performed by the metering device, the complexity of thesystem may be reduced.

The present invention is also defined by the following numberedembodiments.

S1. A system for component interconnection for use in LiquidChromatography comprising a first switching valve; and a secondswitching valve; and a first connecting line fluidly connecting thefirst switching valve to the second switching valve and a secondconnecting line fluidly connecting the first switching valve to thesecond switching valve; and a metering device located in the firstconnecting line.

S2. A system according to embodiment S1 wherein each switching valvecomprises at least four ports and at least two connecting elements,preferably at least five ports and at least three connecting elements.

S3. A system according to any of the preceding embodiments furthercomprising an analytical pump adapted to generate an analytical flow inthe system.

S4. A system according to any of the preceding embodiments furthercomprising a separation column.

S5. A system according to any of the preceding embodiments furthercomprising a trap column.

S6. A system according to any of the preceding embodiments furthercomprising a sample pick up means adapted to retrieve a sample and aseat adapted to receive the sample pick up means.

S7. A system according to the preceding embodiment wherein the system isadapted to connect the metering device to a sample reservoir via thesample pick up means in a sample draw position.

S8. A system according to any of the preceding embodiments wherein thesecond switching valve is adapted to connect the metering device with adead end via the first connecting line in a sample draw position.

S9. A system according to the preceding embodiment wherein the meteringdevice is adapted to generate negative pressure drawing in a sample inthe sample draw position.

S10. A system according to any of the preceding embodiments wherein thesecond switching valve is adapted to connect the metering device and thefirst switching valve to dead-ends via the first connecting line and thesecond connecting line respectively in a pre-compressing position.

S11. A system according to the preceding embodiment wherein the meteringdevice is adapted to generate positive pressure pre-compressingcomponents connected via the first switching valve including the samplein the pre-compressing position.

S12. A system according to the preceding embodiments wherein themetering device is adapted to pre-compress the sample to a pressure of aleast 100 bar, such as at least 1000 bar, more preferably about 1500bar.

S13. A system according to the preceding embodiment and with features ofembodiments S3, S4 and S5 wherein the first switching valve is adaptedto simultaneously connect the analytical pump with the trap column andthe trap column with the separation column in a sample inject position.

S14. A system according to any of the preceding embodiments wherein thesecond switching valve is adapted to connect the metering device to atleast one solvent reservoir, preferably to two distinct solventreservoirs via the first connecting line in a washing position.

S15. A system according to the preceding embodiment wherein the meteringdevice is adapted to wash components connected via the first switchingvalve and the second switching valve in the washing position duringsample analysis.

S16. A system according to any of the preceding embodiments and with thefeatures of embodiment S4 wherein system is adapted to be reloaded witha new sample via the metering device in a reload position during sampleanalysis in the trap column.

S17. A system according to any of the preceding embodiments furthercomprising a waste reservoir.

S18. A system according to the preceding embodiment and with thefeatures of embodiment S3 further adapted to fluidly connect theanalytical pump with the waste reservoir via the second connecting linein a pump purge position.

S19. A system according to any of the preceding embodiments, wherein thesystem is adapted for high performance liquid chromatography.

S20. A system according to any of the preceding embodiments, wherein thefirst switching valve is adapted to assume at least two distinctswitching positions.

S21. A system according to any of the preceding embodiments, wherein thesecond switching valve is adapted to assume at least three distinctswitching positions.

S22. A system according to any of the preceding embodiments and with thefeatures of embodiments S3, S4, S5 and S6 wherein one port of the firstswitching valve is directly fluidly connected to the seat and to thefirst connecting line; and two ports of the first switching valve aredirectly fluidly connected to the trap column; and one port of the firstswitching valve is directly fluidly connected to the separation column;and one port of the first switching valve is directly fluidly connectedto the analytical pump; and one port of the first switching valve isdirectly fluidly connected to the second connecting line.

The term “direct fluid connection” or “directly fluidly connected” isused herein. When a port of a valve is said to be directly fluidlyconnected to another component, this should denote that fluid may flowfrom the port to the other component (and/or vice versa) without havingto pass another port.

S23. A system according to any of the preceding embodiments and with thefeatures of embodiments S14 and S17 wherein one port of the secondswitching valve is directly fluidly connected to the waste reservoir;and one port of the second switching valve is directly fluidly connectedto the first solvent reservoir; and one port of the second switchingvalve is directly fluidly connected to the first connecting line; andone port of the second switching valve is directly fluidly connected tothe second connecting line.

S24. A system according to the preceding embodiments further comprisinga second solvent reservoir and wherein one port of the second switchingvalve is directly fluidly connected to the second solvent reservoir.

S25. A system according to any of the preceding embodiments and with thefeatures of embodiment S6 wherein the first connecting line comprisesone end fluidly connected to the second switching valve; and tubingconnecting the second switching valve to the metering device; and tubingconnecting the metering device to the sample pick up means.

S26. A system according to the preceding embodiment wherein the firstconnecting line is adapted to be separable via the sample pick up meansand the seat.

S27. A system according to any of the preceding embodiments, wherein thefirst switching valve has an identical design as the second switchingvalve.

S28. A system according to any of the preceding embodiments, wherein atleast one of the first and the second switching valve comprises at leastone blind plug.

Note, that connecting lines can also be separable. That is, a connectingline need not always connect the first valve to the second, but caninterrupt this connection for some other function. For example, incertain preferred embodiments, the first connecting line is separable.This can be realized via the sample pick up means and the seat that canbe located on the first connecting line. In the stand by position, thesample pick up means rests in the seat, ensuring that the firstconnecting lines is whole and is connecting the first and secondswitching valves. When, however, the sample pick up means moves to thesample reservoir in order to retrieve the sample, the first connectingline is separated between the sample pick up means and the seat. Whenthe sample pick up means returns to the seat with the sample, the firstconnecting line is whole again.

Below, use embodiments will be discussed. These embodiments areabbreviated by the letter “U” followed by a number. When reference isherein made to a use embodiment, those embodiments are meant.

U1. Use of the liquid chromatography system according to any of thepreceding system embodiments.

U2. Use according to any of the preceding use embodiments and withfeatures of embodiment S14 wherein the second switching valve switchesthe first connecting line to the solvent reservoir and the secondconnecting line to a dead end, and the metering device generatesnegative pressure drawing in the solvent.

U3. Use according to any of the preceding use embodiments, wherein thesecond switching valve switches the first connecting line to a dead end,and the metering device generates negative pressure for sampleretrieval.

U4. Use according to any of the preceding use embodiments with thefeatures of embodiment S5 wherein the second switching valve switchesthe first connecting line and the second connecting line to dead ends,and the metering device generates positive pressure for pre-compressingthe trap column with the sample.

U5. Use according to any of the preceding use embodiments with thefeatures of embodiment S5 wherein the second switching valve switchesthe first connecting line and the second connecting line to dead ends,and the metering device generates negative pressure for decompressingthe trap column.

U6. Use according to any of the preceding use embodiments with thefeatures of embodiments S5, S6 and S17 wherein the first switching valveconnects the first connecting line and the second connecting line withtwo sides of the trap column, and the second switching valve connectsthe first connecting line with a dead end and the second connecting linewith the waste reservoir, and the metering device washes the trap columnand the connecting lines.

U7. Use according to any of the preceding use embodiments and with thefeatures of embodiments S3 and S17 wherein the first switching valveconnects the analytical pump with the second connecting line and thesecond switching valve connects the second connecting line with thewaste reservoir, and the analytical pump provides a flow to cleanitself.

U8. Use according to any of the preceding use embodiments, wherein theuse is a use in liquid chromatography.

U9. Use according to the preceding embodiment, wherein the use is inhigh performance liquid chromatography.

Below, method embodiments will be discussed. These embodiments areabbreviated by the letter “M” followed by a number. When reference isherein made to a method embodiment, those embodiments are meant.

M1. A method for sample loading comprising the steps of

a. providing a liquid chromatography system comprising a first switchingvalve, a second switching valve, a first connecting line fluidlyconnecting the first switching valve to the second switching valve and asecond connecting line fluidly connecting the first switching valve tothe second switching valve, a metering device located in the firstconnecting line, a separation column, a trap column, and an analyticalpump; and

b. loading a sample into the trap column; and

c. fluidly connecting the trap column to the separation column and theanalytical pump to the trap column via the first switching valve andgenerating a flow from the analytical pump to the separation column.

M2. A method according to the preceding embodiment further comprising

d. fluidly connecting the analytical pump to the separation column,wherein the trap column is not fluidly connected to the analytical pumpor the separation column, and maintaining the flow from the analyticalpump to the separation column.

M3. A method according to any of the preceding method embodimentsfurther comprising

e. washing the trap column and the connecting lines; and/or

f. loading another sample into the trap column.

M4. A method according to any of the preceding method embodimentswherein the liquid chromatography system further comprises a sample pickup means adapted to retrieve the sample and a seat adapted to receivethe sample pick up means.

M5. A method according to the preceding embodiment, wherein step b.comprises the sample pick up means being moved to a sample reservoir,the sample being sucked into the sample pick up means and into a tubingsection adjacent to the sample pick up means, the sample pick up meansbeing moved to the seat, the first switching valve being set to providea fluid connection between the seat and the trap column, the samplebeing introduced into the trap column.

M6. A method according to the preceding embodiment, wherein the sampleis sucked into the sample pick up means by means of the metering devicegenerating negative pressure.

M7. A method according to any of the preceding method embodiments andwith features of embodiment M5, wherein the sample is introduced intothe trap column by connecting the first connecting line to a dead endvia the second switching valve and to the trap column via the firstswitching valve, and the metering device pushing the sample from thefirst connecting line to the trap column by generating positivepressure.

M8. A method according to any of the preceding method embodimentswherein the liquid chromatography system further comprises a wastereservoir.

M9. A method according to the preceding embodiment and with the featuresof embodiment M3 wherein step e. comprises fluidly connecting the firstconnecting line to a dead end via the second switching valve and to thetrap column via the first switching valve, and the second connectingline to the trap column via the first switching valve and to the wastereservoir via the second switching valve, and generating a flow from themetering device to the waste reservoir.

M10. A method according to any of the preceding method embodiments withthe features of embodiments M2 and M3 wherein step d. is performedconcurrently with steps e. and/or f.

M11. A method according to any of the preceding method embodiments,wherein the method comprises pressurizing the trap column after loadingthe sample into it.

M12. A method according to the preceding embodiment, wherein the trapcolumn is pressurized when the trap column is not fluidly connected tothe analytical pump.

M13. A method according to any of the preceding two embodiments, whereinthe trap column is pressurized when the trap column is not fluidlyconnected to the separation column.

M14. A method according to any of the preceding 3 embodiments whereinthe metering device pressurizes the trap column.

M15. A method according to any of the preceding method embodiments,wherein the method comprises depressurizing the trap column aftersupplying the sample from the trap column to the separation column.

M16. A method according to the preceding embodiment, wherein the trapcolumn is depressurized when the trap column is not fluidly connected tothe analytical pump.

M17. A method according to any of the preceding two embodiments, whereinthe trap column is depressurized when the trap column is not fluidlyconnected to the separation column.

M18. A method according to any of the preceding 3 embodiments, whereinthe metering device depressurizes the trap column.

M19. A method according to any of the preceding method embodiments andwith the features of embodiment M11 wherein the trap column ispressurized to a pressure of at least 100 bar, preferably 1000 bar, morepreferably at least 1500 bar.

M20. A method according to any of the preceding method embodimentswherein the metering device loads the sample into the trap column.

M21. A method according to any of the preceding method embodiments andwith the features of embodiment M3 wherein the metering device washesthe trap column and the connecting lines by generating positivepressure.

BRIEF DESCRIPTION OF THE DRAWINGS

The above features along with additional details of the invention, aredescribed further in the examples below, which are intended to furtherillustrate the invention but are not intended to limit its scope in anyway.

FIG. 1 schematically depicts a liquid chromatography system according toone embodiment of the invention;

FIG. 2 schematically depicts features of a switching valve according toone embodiment of the invention;

FIG. 3 schematically depicts filling of the metering device with solventaccording to one embodiment of the invention;

FIG. 4 schematically depicts drawing in of the sample according to oneembodiment of the invention;

FIG. 5 schematically depicts sample injection into the trap columnaccording to one embodiment of the invention;

FIG. 6 schematically depicts pre-compression of the trap columnaccording to one embodiment of the invention;

FIG. 7a schematically depicts back flush injection of the sample intothe separation column according to one embodiment of the invention;

FIG. 7b schematically depicts forward flush injection of the sample intothe separation column according to one embodiment of the invention;

FIG. 8 schematically depicts decompression of the trap column accordingto one aspect of the invention;

FIG. 9 schematically depicts washing of the system according to oneaspect of the invention;

FIG. 10 schematically depicts analytical pump cleaning according to oneaspect of the invention.

FIG. 11 schematically depicts a switching valve with a port arrangementaccording to one aspect of the invention.

DETAILED DESCRIPTION OF EMBODIMENTS

In the following, exemplary embodiments of the invention will bedescribed, referring to the figures. These examples are provided toprovide further understanding of the invention, without limiting itsscope.

In the following description, a series of features and/or steps aredescribed. The skilled person will appreciate that unless required bythe context, the order of features and steps is not critical for theresulting configuration and its effect. Further, it will be apparent tothe skilled person that irrespective of the order of features and steps,the presence or absence of time delay between steps, can be presentbetween some or all of the described steps.

It is noted that not all of the drawings carry all the reference signs.Instead, in some of the drawings, some of the reference signs have beenomitted for sake of brevity and simplicity of illustration.

FIG. 1 depicts a liquid chromatography system 1000 according to oneaspect of the invention. The system 1000 comprises a sample reservoir 2comprising a sample to be analysed. The system 1000 further comprises aseparation column 4 and a trap column 6. The system comprises a samplepick up means 8, shown here as a needle 8 and a seat 10, shown here asneedle seat 10. The liquid chromatography system 1000 comprises ananalytical pump 12 and a pump solvent reservoir 13. FIG. 1 further showstwo solvent reservoirs 14 and 16, but in other embodiments of the system1000 one solvent reservoir 14 or 16 can be used. The system 1000 furthercomprises a waste reservoir 18. The liquid chromatography system alsocomprises a metering device 100. The metering device 100 comprises aport 102, a port 104, a piston 106 and a housing 108. The liquidchromatography system 1000 further comprises two switching valves, afirst or left switching valve 200 and a second or right switching valve400. The system 1000 also comprises tubing or capillaries connectingvarious components. Tubing 510 connects port 102 of the metering device100 with the needle 8. Tubing 512 can be directly adjacent to the needle8. Between the metering device 100 and the needle 8, past tubing 512(which tubing 512 may also be referred to as sample loop 512), system1000 can further comprise a buffer loop 514. The buffer loop 514 mayprovide an additional length of tubing to allow movement of the needle8. Second connecting line 520 (or tubing 520) connects the firstswitching valve 200 directly to the second switching valve 400. Tubing530 connects port 104 of the metering device 100 with the secondswitching valve 400. Tubing 510, 514, 512 and 530 may collectively bereferred to as a first connecting line 500. That is, the firstconnecting line 500 connects the first switching valve 200 with thesecond switching valve 400 via the needle 8 and needle seat 10 on theone hand, and via the metering device 100 on the other hand.

The second connecting line 520 is connected directly with both switchingvalves 200, 400, while the first connecting line 500 is also comprisingthe metering device 100. In this embodiment, the connecting line is alsoseparable through a needle 8/needle seat 10 connection. However, anembodiment without this connection in the first connecting line 500 isalso possible.

The liquid chromatography system 1000 is adapted to retrieve a samplefrom the sample reservoir 2. This can be achieved via the sample pick upmeans 8. The sample pick up means can travel to the sample reservoir 2(see FIG. 4), retrieve the sample, and travel back to the needle seat10. Retrieval of the sample can be done via a pressure differencegenerated by the metering device 100. The metering device 100 can moveits piston 106 outward of the metering device housing 108 to draw insolvent 14 or solvent 16, and then move further outward to generate thepressure difference for sucking in the sample from the sample reservoir2. This can be achieved by switching the first connecting line 510 to adead end via the second switching valve 400. The sample can then beintroduced into the system via needle 8 and optionally also tubing 512.The sample can be first stored in the needle 8 and optionally in thesample loop 512. This is further discussed in relation to FIGS. 3 and 4.

The liquid chromatography system 1000 is further adapted to introducethe sample into the trap column 6. This can be done via the meteringdevice 100 as well, by moving its piston 106 and generating a pressuredifference. This is further discussed in relation to FIG. 5.

The liquid chromatography system 1000 is further adapted to pre-compressthe trap column 6 to the pressure of the separation column 4. In HighPerformance Liquid Chromatography (HPLC), the pressures at which thesample is separated into its constituents in the separation column 4 canexceed 100 bar. It can be on the order of a few hundred bar or exceed1.000 bar, such as 1.500 bar. Therefore, the pressure within theseparation column can significantly differ from the pressure within theparts of the system in contact with the atmosphere, such as the needle8. The pre-compressing then allows to equilibrate the pressure withinthe system. Pre-compressing can be done via the metering device 100 bygenerating a positive pressure via the piston 106. This can be achievedby switching both the first connecting line 500 and the secondconnecting line 520 to dead ends via the second switching valve 400.This is further discussed in relation to FIG. 6.

The system 1000 is also adapted to inject the sample from the trapcolumn 6 to the separation column 4 by means of the analytical flow.This can be done by guiding the sample by means of the analytical pump12. The injection of the analytical flow into the separation column 4can be done in a back flush and in a forward flush manner via differentpositions of the switching valve 200. That is, the flow from the trapcolumn 6 to the separation column 4 can ensue in the same direction asthe flow from the needle 8 to the trap column 6 above (forward flush).The flow from the trap column 6 to the separation column 4 can alsoensue in the opposite direction to the flow from the needle 8 to thetrap column 6 above (backward flush). Switching between the two optionscan be done via different switching positions of the valve 200 withoutdismantling the system 1000. This is further explained in relation toFIGS. 7a and 7 b.

The liquid chromatography system 1000 is also adapted to decompress thetrap column 6. After sample injection into the separation column 4, thesystem 1000 is at analytical pressure, which, as discussed above, can beon the order of several hundred bar or even above 1.000 bar. Beforereconnecting the trap column 6 with the outside, which is at atmosphericpressure, it can be advantageous to decompress it in a controlledmanner. This can be done via the metering device 100 by displacing thepiston 106 in order to reduce the pressure within the trap column 6. Asthe pre-compressing, this requires that both the first connecting line500 and the second connecting line 520 are switched to dead ends via thesecond switching valve 400. This is further discussed in relation toFIG. 8. The controlled decompression may be advantageous for differentreasons. By means of the controlled decompression, no uncontrolled andmore rapid decompression occurs. Thus, the controlled decompressionleads to less abrasion on the valve 200 and other components and alsoprevents fluid from rapidly exiting the system (which could be a riskfor a user). Furthermore, the controlled decompression also lowers therisk of components outgassing in the fluid in the system.

The system 1000 is also adapted to clean or wash itself. Particularly,the metering device 100 can draw in solvent from solvent reservoirs 14or 16 by displacing the piston 106 and generating a pressure difference.The solvent can then be passed through the buffer loop 514, the needle8, the needle seat 10 and the trap column 6 in order to remove anyresidual components of the sample or of the flow. These can then bewashed by the solvent and delivered into the waste reservoir 18.Advantageously, the system 1000 is adapted to allow the metering device100 to wash the trap column 6 and the tubing or capillaries while thesample is being analysed in the separation column 4. This leads to moreefficient system operation. This is further discussed in relation toFIG. 9.

The liquid chromatography system 1000 can also be adapted to clean orpurge the analytical pump 12. The pump solvent reservoir 13 can bereplaced and the pump 12 washed with the residual fluid delivered intothe waste reservoir 18. The analytical pump 12 and the waste reservoir18 can in this case be connected via the second connecting line 520.This is further discussed in relation to FIG. 10.

FIG. 2 schematically illustrates a switching valve such as the first (orleft) switching valve 200 and/or the second (or right) switching valve400. Each switching valve 200 may comprise a stator 210 and a rotor 220.The stator 210 may comprise ports 212 to which different elements may beconnected (e.g., in the embodiment depicted in FIG. 1, each of theneedle 8, the analytical pump 12, the separation column 4 and the secondconnecting line 520 to the other switching valve 400 is fluidlyconnected to one port of the switching valve 200, respectively, and thetrap column 6 is fluidly connected to two ports of this switching valve200). More particularly, these components are each directly fluidlyconnected to the respective port or the respective ports. When acomponent is said to be directly fluidly connected to a port, thisshould denote that there is a fluid connection between this componentand the port (that is, fluid may flow from the component to the portand/or vice versa) and that this fluid connection is such that there isno other port in this connection. For example, the central port in theleft valve 200 in FIG. 1 is directly fluidly connected to the pump 12.This central port in FIG. 1 is not fluidly connected, e.g., to themetering device 100, but is also fluidly connected to the separationcolumn 4. However, the connection between the central port and theseparation column 4 is not a direct fluid connection, as fluid flowingfrom this central port would have to travel via another port beforereaching the separation column. With reference to FIG. 2, the rotor 220may comprise connecting elements 222, such as grooves 222, that mayinterconnect different ports 212 of the stator element 210. For example,FIG. 1 depicts a configuration where each connecting element 222 of therotor of the left distribution valve 200 interconnects two ports of saidswitching valve, respectively, while the stator and the rotor of thesecond switching valve 400 are in such a configuration that only two ofthe ports in the second switching valve are interconnected to oneanother (that is, the ports connecting the second connecting line 520and waste reservoir 18 are connected by a connecting element of thesecond switching valve 400). It will be understood that whenever twoelements are described to be connected to one another, this denotes afluid connection, i.e., a connection where a fluid may flow from oneelement to the other, unless otherwise specified or unless clear to theskilled person that something different is meant.

Though not depicted, it is noted that there may also be provided blindplugs closing off one or more ports of the switching valves 200, 400. Inparticular, the distributor valves 200, 400 may be identical to oneanother (and only differ by the use of the blind plugs), which maysimplify the productions process. However, the distributor valves 200,400 may also be different to each other.

FIG. 3 schematically depicts filling of the metering device 100 withsolvent according to one embodiment of the invention. In other words,FIG. 3 depicts the choice and retrieval of the solvent and cleaningagent. The right switching valve 400 is fluidly connecting the meteringdevice 100 to the solvent reservoir 14 via the first connecting line500. Note, that connection to solvent reservoir 16 would also bepossible by a different arrangement of one of the connecting elements.The piston 106 of the metering device 100 can now move back in order tocreate negative pressure and draw up solvent from the solvent reservoir14 and partially fill the metering device 100 with it (the meteringdevice 100 needs to have enough residual space to also draw in thesample). The metering device 100 may then have enough solvent in orderto guide the sample into the trap column 6 for the trapping. Theselection and retrieval of the solvent is possible because the firstconnecting line 500 is, on one hand, connected with the desired solvent14 (or 16) through the second switching valve 400 and, on the otherhand, is fluidly connected with the second connecting line 520. Thisallows negative pressure to be generated allowing the intake of thesolvent through the metering device 100.

FIG. 4 schematically depicts drawing in of the sample according to oneembodiment of the invention. The needle 8 moves to the sample reservoir2, thus separating the first connecting line 500. The second switchingvalve 400 closes the supply line to the metering device 100 by switchingfrom the solvent reservoir 14 to a dead end. In this way, the meteringdevice 100 can generate negative pressure by retreating its piston 106further to draw in the sample through the needle 8. Since the secondconnecting line 520 is switched to a dead end via the second connectingvalve 400, the metering device 100 can generate negative pressureallowing the intake of the solvent through the metering device 100.

FIG. 5 schematically depicts sample injection into the trap column 6according to one embodiment of the invention. In other words, fluidiccomponents including the trap column 6 are washed in this configurationand the sample is trapped in the trap column 6. More particularly, theneedle 8 now returns to the needle seat 10, and the first connectingline 500 is now again connecting both switching valves 200, 400. Thesample can be meanwhile stored in the sample loop 512. The firstconnecting line 500 is again switched to a dead end via the secondswitching valve 400. The metering device 100 can now generate a positivepressure by moving its piston 106 back into the housing 108. In thisway, the sample can be pushed in the other direction through the needle8 into the trap column 6. The right valve 400 connects a side of thetrap column 6 opposite to the one the sample arrived through with thewaste reservoir 18. In this position, the piston 106 of the meteringdevice 100 can move forward and therefore push the sample with thepreviously raised trap solvent to the trap column 6. Components which donot adhere to the trap column 6 get pushed out to the waste reservoir18. This process may be repeated if the right valve 400 again connectsthe port 104 (which may also be referred to as the rear output) of themetering device 100 with the solvent reservoirs 14 or 16 and thereforeallows the metering device 100 to raise fresh trap solvent. That is,more trap solvent may be introduced into the section of the systemfluidly connected to the trap column 6 in FIG. 5. To do so, valve 400 ismoved to connect tubing 530 to solvent reservoir 14 or 16 (that is theconfiguration of valve 400 in FIG. 3), and thus port 104 is opened andport 102 of metering device 100 is closed (by being switched to a deadend). The second switching valve 400 also switches the second connectingline 520 to a dead end, allowing for pressure build-up. When the piston106 is moved back in such a configuration, solvent is drawn from thesolvent reservoir 14 (or 16) into the metering device 100. Subsequently,port 104 can be closed (by being connected to a dead end) and port 102be opened (i.e. not connected to a dead end). Then, piston 106 may bemoved forward to supply the solvent into tubing section 510 to therebysupply more solvent towards the trap column 6. This process may also bereferred to as trapping (and retrapping) the sample.

That is, with general reference to FIGS. 4 and 5, it is noted that, forthe washing phase or for another sample retrieval for trapping, thefirst connecting line 500 is switched to a dead end via the second valve400 to either draw up the sample and/or guide the cleaning solution. Forthis purpose, the first connecting line 500 remains fluidly connectedwith the second connecting line 520 via the first valve 400, and thesecond connecting line 520 is connected with the waste 18 via the secondvalve 400.

FIG. 6 schematically depicts pre-compression of the trap column 6according to one embodiment of the invention. The right valve 400switches to an intermediate position, i.e., to the position where boththe first connecting line 500 (or, more specifically, its sectionreferred to as tubing 530) and the second connecting line 520 areswitched to a dead end. The piston 106 in the metering device 100 movesforward, such that volume in the tubing 510 (which includes the bufferloop 514), the trap column 6, the metering device 106 and theconnections is compressed. It can be compressed until analyticalpressure is reached. Though not depicted, the system 1000 may alsocomprise a pressure sensor. The pressure sensor may be fluidly connectedto the metering device 100 (e.g., it may be disposed between meteringdevice 100 and the second switching valve 400). Thus, whenprecompressing a section of the system 1000 (as discussed), one maymonitor the pressure in this section—e.g., to bring this pressure to theanalytical pressure. The sensor may also be used for monitoring thedecompression of a section of the system. By the pre-compression step,the sample in the trap column 6 may be brought to an elevated pressure,such as to the analytical pressure. The controlled pre-compression stepmay reduce pressure spikes in the system, thereby reducing wear andleading to a longer service life of the system. Further, not havingpressure spikes also reduced the likelihood of the sample being mixedwith solvent, i.e., dispersion. Having a less dispersed sample leads toa more defined peak in subsequent analysis, thereby resulting in animproved analysis.

In some previously known liquid chromatography embodiments, the valveresponsible for the injection process was also responsible for thepre-compression position switching. However, this would require anintermediate position of the valve, so that both ends of thepre-compressed elements (the buffer loop and the trap column) would haveno connection to the atmosphere and simultaneously the analytical flowto the separation column is not interrupted. In the presently disclosedembodiments, this is done by spatially separating both functions(injection/pre-compression) via two switching valves 200, 400 that areconnected by at least two connection lines 500, 520. The samplepre-compression position can then be assumed via the second valve 400,by switching the ends of the two connecting lines 500, 520 to dead ends.The connecting lines 500, 520 can remain fluidly connected via the firstconnecting valve 200. The metering device 100 can now pre-compress thebuffer loop 514, the trap column 6 and various tubing to system pressure(that is, the pressure of the separation column 4).

The pre-compression position can be assumed via the second valve 400 inthis embodiment, by switching the ends of the first and secondconnecting lines 500 and 520 to a dead end. The connecting lines 500,520 remain fluidly connected via the first valve 200. Now, the meteringdevice 100 can pre-compress the buffer loop and/or the trap column 6 tosystem pressure.

FIG. 7a and FIG. 7b schematically depict injection of the sample intothe separation column 4 according to one embodiment of the invention.

FIG. 7a demonstrates injection of the sample via back flushing. The leftvalve 200 is switched such that the trap column 6 is introduced into theanalytical flow in such a way that the analytical flow pushes the sampleback out the side it came from (backward flush). That is, the flowdirection through the trap column 6 is opposite to the flow direction inwhich the trap column 6 was supplied with the sample. Put differently, afirst end of the trap column 6 that has been upstream from a second endof the trap column 6 when being provided with the sample is nowdownstream from this second end when the analytical flow is providedthrough the trap column 6.

FIG. 7b demonstrates injection of the sample via forward flushing. Thatis, the flow direction through the trap column 6 is parallel to the flowdirection with which the trap column 6 was supplied with the sample. Putdifferently, a first end of the trap column 6 that has been upstream toa second end of the trap column 6 when being provided with the sample isnow also upstream to this second end when the analytical flow isprovided through the trap column 6.

Note, that switching between configurations shown in FIGS. 7a and 7b isdone by moving the connecting elements 222 (not shown) of the firstswitching valve 200. That is, the process of switching between the backflush and forward flush configurations can be done without dismountingthe apparatus and without hardware changes. It is not necessary tomanually or automatically switch the ports 212 (not shown) of theswitching valve 200 to which the analytical pump 12, the trap column 6and the separation column 4 are connected. These components remainconnected to the same ports 212 in the backward and forward flushconfigurations. This is achievable due to the topology of the switchingvalve 200 and the flexibility in the connection of various pairs ofports 212 with the connecting elements or grooves 222. Therefore, in thepresent configuration, switching between the backward flush as in FIG.7a and the forward flush as in FIG. 7b is simple and fast, and can bedone between experiments without reconfiguring the liquid chromatographysystem 1000.

FIG. 8 schematically depicts decompression of the trap column accordingto one aspect of the invention. This configuration is similar to the onedepicted in FIG. 6. Again, the trap column 6 is fluidly connected tosecond connecting line 520, connecting valves 200 and 400 and to thefirst connecting line 500 (more specifically, to its section referred toas tubing 510) providing a connection to the metering device 100. Bymoving the piston 106 back, the pressure still present in the portion ofthe system 1000 fluidly connected to the trap column 6 (including thebuffer loop 514, the metering device 100 and the connections) can bereduced. That is, this configuration may also be referred to as thedecompress state. As discussed, the controlled decompression may beadvantageous, as it may lead to less abrasion, may prevent fluids fromrapidly exiting the system and may reduce the risk of componentsoutgassing.

FIG. 9 schematically depicts washing of the system according to oneaspect of the invention. The first connecting line 500 is now switchedto a dead end via the second switching valve 400 so that it can guidethe cleaning solution (alternatively, draw up a new sample andtrap/guide it). The first connecting line 500 therefore remains fluidlyconnected with the second connecting line 520 via the trap column 6 andthe first valve 200, and the second connecting line is connected withthe waste reservoir 18 via the second switching valve 400. The trapcolumn 6 is here fluidly connected to the waste reservoir 18 via thesecond connecting line 520. The metering device 100 can then washitself, the first connecting line 500 including tubing 510, the bufferloop 514, the needle 8 and the needle seat 10, as well as the trapcolumn 6 and the second connecting line 520. To do this, the rightswitching valve 400 may be switched so that the metering device 100 candraw up one of the solvents from solvent reservoirs 14, 16 and thenswitch back to inject solvent into the system for washing. The meteringdevice 100 can be refilled multiple times for thorough washing. In thisposition, trapping of a new sample by the trap column 6 is alsopossible, while the first sample is undergoing analysis in theseparation column 4. That is, the separation column 4 is fluidlyconnected with the analytical pump 12 without the trap column 6 in theway. The needle 8 can then retrieve a new sample and trap it in the trapcolumn 6 while analysis of the previous sample is still underway in theseparation column 4. This can lead to significant time saving and systemefficiency. In other words, after the sample in the inject position isguided from the trap column 6 to the separation column 4 by theanalytical pump 12, the first valve 200 can be switched back to the trapposition or the wash position. In this position, the washing of fluidiccomponents including the trap column 6 and/or trapping of a new sampleby the trap column 6 are possible, while the previous sample is passingthrough the separation column 4 and is analysed, which saves time andtherefore enhances the efficiency. It is also noted that washing may beperformed simultaneously with equilibrating and/or sample analysis.Equilibrating may be done by means of the first (left) valve 200 byhaving the analytical pump 12 fluidly connected with the separationcolumn 4 (i.e., valve 200 may not be switched when equilibrating) andthe second (right) valve 400 being iteratively switched. It is generallynoted that free selection of solvent or cleaning solution is alsopossible by means of the second valve 400. Thus, the selectivity may beincreased.

It may also be advantageous that the metering device 100 can be used asa metering pump, a pre-compression device, a cleaning pump and atrapping or loading pump. This leads to an efficient system requiringless space and operating in a particularly optimized way.

FIG. 10 schematically depicts analytical pump cleaning according to oneaspect of the invention. In this position, the analytical pump 12 andthe pump solvent reservoir 13 are fluidly connected with waste reservoir18 via the second connecting line 520. The previously used pump solventcan now be quickly replaced in the intake lines and in the head of theanalytical pump 12. The analytical pump 12 can then be washedeffectively, using the direct connection to the waste reservoir 18. Thereplacement of one pump solvent with another may also function moreefficiently, as a higher flow may be provided (as there is no columnincreasing the flow resistance in the path between the analytical pump12 and the waste reservoir 18). The pump solvent may be selected bymeans of a solvent selector valve.

FIG. 11 schematically depicts a switching valve with a port arrangementaccording to one aspect of the invention. The central port 2121 isadapted to be fluidly connected with any of the other ports 2122, 2123,2123, 2125 and 2126. This is possible via the connecting elements orgrooves 222. Particularly, the central port 2121 is adapted to beconnected to any other port via the central connecting element 2221. Thearrangements of the curved connecting elements 2222 and 2223 allows theswitching valve 200, 400 to simultaneously connect the central port 2121with another port and use the other connecting elements for furtherconnection of ports allowing for multiple switching positions.

As used herein, including in the claims, singular forms of terms are tobe construed as also including the plural form and vice versa, unlessthe context indicates otherwise. Thus, it should be noted that as usedherein, the singular forms “a,” “an,” and “the” include pluralreferences unless the context clearly dictates otherwise.

Throughout the description and claims, the terms “comprise”,“including”, “having”, and “contain” and their variations should beunderstood as meaning “including but not limited to”, and are notintended to exclude other components.

The term “at least one” should be understood as meaning “one or more”,and therefore includes both embodiments that include one or multiplecomponents. Furthermore, dependent claims that refer to independentclaims that describe features with “at least one” have the same meaning,both when the feature is referred to as “the” and “the at least one”.

It will be appreciated that variations to the foregoing embodiments ofthe invention can be made while still falling within the scope of theinvention can be made while still falling within scope of the invention.Features disclosed in the specification, unless stated otherwise, can bereplaced by alternative features serving the same, equivalent or similarpurpose. Thus, unless stated otherwise, each feature disclosedrepresents one example of a generic series of equivalent or similarfeatures.

Use of exemplary language, such as “for instance”, “such as”, “forexample” and the like, is merely intended to better illustrate theinvention and does not indicate a limitation on the scope of theinvention unless so claimed. Any steps described in the specificationmay be performed in any order or simultaneously, unless the contextclearly indicates otherwise. Furthermore, when a step (X) is said toprecede another step (Z), this does not imply that there is no stepbetween steps (X) and (Z). That is, step (X) preceding step (Z)encompasses the situation that step (X) is performed directly beforestep (Z), but also the situation that (X) is performed before one ormore steps (Y1), . . . , followed by step (Z). Correspondingconsiderations apply when terms like “after” or “before” are used.

All of the features and/or steps disclosed in the specification can becombined in any combination, except for combinations where at least someof the features and/or steps are mutually exclusive. In particular,preferred features of the invention are applicable to all aspects of theinvention and may be used in any combination.

What is claimed is:
 1. A system for interconnection of components foruse in liquid chromatography comprising: A) a first switching valve; B)a second switching valve; C) a first connecting line fluidly connectingthe first switching valve to the second switching valve; D) a secondconnecting line fluidly connecting the first switching valve to thesecond switching valve; E) a metering device, wherein the firstconnecting line comprises the metering device; wherein the secondswitching valve is adapted to connect the metering device to at leastone solvent reservoir via the first connecting line in a washingposition; and F) a trap column directly fluidically connected to twoports of the first switching valve; wherein the first connecting lineincludes a first tube and a second tube, the first tube fluidlyconnecting the metering device to the first switching valve, the secondtube fluidly connecting the metering device to the second switchingvalve; wherein in a sample draw position, the second switching valve isadapted to connect the metering device with a first dead end via thesecond tube; wherein in a pre-compressing position, the second switchingvalve is adapted to connect the metering device to the first dead end onthe second switching valve via the second tube, and connect the meteringdevice to a second dead end on the second switching valve via the secondconnecting line; wherein in the pre-compressing position, the meteringdevice is adapted to generate a positive pressure pre-compressing thetrap column, wherein the trap column is fluidly connected via the firstswitching valve to the first connecting line and to the metering device;and wherein the metering device is adapted to wash the componentsconnected via the first switching valve and the second switching valvein the washing position during a sample analysis, wherein the componentscomprise a needle.
 2. The system according to claim 1 furthercomprising: G) a separation column, wherein in the washing position, themetering device is adapted to wash the trap column connected via thefirst switching valve during a sample analysis in the separation column.3. The system according to claim 2, wherein the system is adapted to bereloaded with a new sample via the metering device in a reload positionduring the sample analysis in the separation column.
 4. The systemaccording to claim 3 further comprising: H) an analytical pump adaptedto generate an analytical flow in the system; I) the needle adapted toretrieve a sample, J) a seat adapted to receive the needle; and K) awaste reservoir, wherein a second port of the first switching valve isdirectly fluidly connected to the seat and then to the first connectingline; a third port and a fifth port both of the first switching valveare both directly fluidly connected to the trap column; a fourth port ofthe first switching valve is directly fluidly connected to theseparation column; a first port of the first switching valve is directlyfluidly connected to the analytical pump; a sixth port of the firstswitching valve is directly fluidly connected to the second connectingline; a seventh port of the second switching valve is directly fluidlyconnected to the waste reservoir; an eighth port of the second switchingvalve is directly fluidly connected to the first solvent reservoir; aninth port of the second switching valve is directly fluidly connectedto the first connecting line; and a tenth port of the second switchingvalve is directly fluidly connected to the second connecting line. 5.The system according to claim 4, wherein the second tube is fluidlyconnecting the metering device to the needle.
 6. A system forinterconnection of components for use in liquid chromatographycomprising: A) a first switching valve; B) a second switching valve; C)first connecting line fluidly connecting the first switching valve tothe second switching valve; D) a second connecting line fluidlyconnecting the first switching valve to the second switching valve; andE) a metering device, wherein the first connecting line comprises themetering device; wherein the second switching valve is adapted toconnect the metering device to at least one solvent reservoir via thefirst connecting line in a washing position, and F) a trap columndirectly fluidically connected to two ports of the first switchingvalve; wherein the metering device is adapted to wash the componentsconnected via the first switching valve and the second switching valvein the washing position during a sample analysis, wherein the componentscomprise a needle; and wherein in a pre-compressing position, themetering device is adapted to generate a positive pressurepre-compressing the trap column, wherein the trap column is fluidlyconnected via the first switching valve to the first connecting line andto the metering device.
 7. The system according to claim 6, wherein thefirst connecting line includes a first tube and a second tube, the firsttube fluidly connecting the metering device to the first switchingvalve, the second tube fluidly connecting the metering device to thesecond switching valve.
 8. The system according to claim 7, wherein in asample draw position, the second switching valve is adapted to connectthe metering device with a first dead end via the second tube.
 9. Thesystem according to claim 8, wherein in the sample draw position, themetering device is adapted to generate a negative pressure drawing in asample.
 10. The system according to claim 8, wherein in apre-compressing position, the second switching valve is adapted toconnect the metering device to the first dead end on the secondswitching valve via the second tube, and connect the metering device toa second dead end on the second switching valve via the secondconnecting line.
 11. The system according to claim 6 further comprising:G) a separation column, wherein in the washing position, the meteringdevice is adapted to wash the trap column connected via the firstswitching valve during a sample analysis in the separation column. 12.The system according to claim 11, wherein the system is adapted to bereloaded with a new sample via the metering device in a reload positionduring the sample analysis in the separation column.
 13. The systemaccording to claim 12 further comprising: H) an analytical pump adaptedto generate an analytical flow in the system; I) the needle adapted toretrieve a sample, J) a seat adapted to receive the needle; and K) awaste reservoir, wherein a second port of the first switching valve isdirectly fluidly connected to the seat and then to the first connectingline; a third port and a fifth port both of the first switching valveare both directly fluidly connected to the trap column; a fourth port ofthe first switching valve is directly fluidly connected to theseparation column; a first port of the first switching valve is directlyfluidly connected to the analytical pump; a sixth port of the firstswitching valve is directly fluidly connected to the second connectingline; a seventh port of the second switching valve is directly fluidlyconnected to the waste reservoir; an eighth port of the second switchingvalve is directly fluidly connected to the first solvent reservoir; aninth port of the second switching valve is directly fluidly connectedto the first connecting line; and a tenth port of the second switchingvalve is directly fluidly connected to the second connecting line. 14.The system according to claim 13, wherein the second tube is fluidlyconnecting the metering device to the needle.
 15. A system forinterconnection of components for use in liquid chromatographycomprising: A) a first switching valve; B) a second switching valve; C)a first connecting line fluidly connecting the first switching valve tothe second switching valve; D) a second connecting line fluidlyconnecting the first switching valve to the second switching valve; andE) a metering device, wherein the first connecting line comprises themetering device; wherein the second switching valve is adapted toconnect the metering device to at least one solvent reservoir via thefirst connecting line in a washing position, and wherein the meteringdevice is adapted to wash the components connected via the firstswitching valve and the second switching valve in the washing positionduring a sample analysis, wherein the components comprise a needle inthe first connecting line.
 16. The system according to claim 15, whereinthe first connecting line includes a first tube and a second tube, thefirst tube fluidly connecting the metering device to the first switchingvalve, the second tube fluidly connecting the metering device to thesecond switching valve.
 17. The system according to claim 16, wherein ina sample draw position, the second switching valve is adapted to connectthe metering device with a first dead end via the second tube.
 18. Thesystem according to claim 17, wherein in the sample draw position, themetering device is adapted to generate a negative pressure drawing in asample.
 19. The system according to claim 17, wherein in apre-compressing position, the second switching valve is adapted toconnect the metering device to the first dead end on the secondswitching valve via the second tube, and connect the metering device toa second dead end on the second switching valve via the secondconnecting line.
 20. The system according to claim 19 furthercomprising: F) a trap column directly fluidically connected to two portsof the first switching valve; wherein in the pre-compressing position,the metering device is adapted to generate a positive pressurepre-compressing the trap column, wherein the trap column is fluidlyconnected via the first switching valve to the first connecting line andto the metering device.
 21. The system according to claim 20 furthercomprising: G) a separation column, wherein in the washing position, themetering device is adapted to wash the trap column connected via thefirst switching valve during a sample analysis in the separation column.22. The system according to claim 21, wherein the system is adapted tobe reloaded with a new sample via the metering device in a reloadposition during the sample analysis in the separation column.